Allocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.llocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.
Definition of roost. 1  1a : a support on which birds restb : a place where winged animals and especially birds customarily roost. 2  2 : a group of birds roosting together.
(roÍost) n. 1. A place where winged animals, especially birds or bats, rest or sleep. 2. A group of animals in a roost. 3. A place for temporary rest or sleep: One corner of the Panhandle served as a roost for outlaws, thieves, and killers (Timothy Egan).